TheZymurgist
Well-Known Member
I thought I'd get more discussion here. This is in reference to the article posted on the home page. I think it's a great write up, and I know there are many homebrewers that use this or similar methods for aeration. I'm only curious about one aspect of my understanding of the life cycle of yeast.
Here's the article:
https://www.homebrewtalk.com/Venturi-Aeration-Experiment.html
And here's my comment:
The author of the article states that of two batches, one using the Venturi method, one using stirring to aerate, the Venturi method had a shorter lag time. My understanding is that the lag phase is the time during which the yeast are reproducing in the presence of oxygen. My question is, if there is more oxygen, won't the yeast be focused on reproduction longer than if there were less? And if the yeast are reproducing, they aren't expelling as much CO2 which creates the krausen, which we interpret as the lag phase.
Starters and cell count are irrelevant to this discussion, since I'm wanting to compare how the yeast acts relative to dissolved oxygen.
Practically, what have you all experienced? Assuming no other factors were changed, have you experienced longer or shorter lag times with the addition of oxygen? Unfortunately, I started aerating with pure O2 at the same time I began using starters, so I can't comment on that single factor.
Here's the article:
https://www.homebrewtalk.com/Venturi-Aeration-Experiment.html
And here's my comment:
"Someone correct me if I'm wrong, but I thought the addition of oxygen actually increases the "lag phase." In the presence of oxygen, yeast cells are focused on reproduction, and while they are multiplying, they are not
expelling ethanol and CO2, at least not at the same rate as during anaerobic respiration. Which means, with proper aeration, while the yeast are multiplying, there won't be any significant krausen.
In my experience, adding
oxygen after krausen has formed has caused the krausen to fall, which means the yeast are switching from anaerobic respiration (producing enthanol and CO2, which causes krausen to form) to aerobic respiration (reproduction.)
If
that's the case, and you had two separate batches, one aerated, one not, all else equal, the one aerated should have a longer "lag time" or take longer to form krausen because the yeast are focused on reproduction rather
than expelling ethanol and CO2.
Or am I wrong? Have you all experienced shorter lag times with the addition of oxygen (all else equal, of course)?"
The author of the article states that of two batches, one using the Venturi method, one using stirring to aerate, the Venturi method had a shorter lag time. My understanding is that the lag phase is the time during which the yeast are reproducing in the presence of oxygen. My question is, if there is more oxygen, won't the yeast be focused on reproduction longer than if there were less? And if the yeast are reproducing, they aren't expelling as much CO2 which creates the krausen, which we interpret as the lag phase.
Starters and cell count are irrelevant to this discussion, since I'm wanting to compare how the yeast acts relative to dissolved oxygen.
Practically, what have you all experienced? Assuming no other factors were changed, have you experienced longer or shorter lag times with the addition of oxygen? Unfortunately, I started aerating with pure O2 at the same time I began using starters, so I can't comment on that single factor.